JPS6327233B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a servo steering device for an automobile, more specifically a steering shaft, a steering gear mechanism,
The present invention relates to a servo steering system for an automobile, which includes a tie rod that transmits the motion obtained by the steering shaft and the steering gear mechanism to the wheels of the automobile, and a two-chamber cylinder piston unit used as a hydraulic steering damper.

In this type of steering system, a cylinder-piston unit of a steering damper has conventionally been used as a device for generating auxiliary force, so that less effort is required during steering. To control such steering dampers, adjustment devices are used which are controlled by electronic control units. In this case, the electronic control unit processes the rotational direction signal obtained from the steering column. The sensors necessary for this purpose are arranged between the steering shaft and the steering gear mechanism. However, it has been found that such sensors are not very desirable, although they are very expensive. Furthermore, it has been found that if such a sensor were to be activated, it would have to be placed directly into the steering gear mechanism, which is undesirable for safety reasons.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a servo steering system for an automobile that overcomes these conventional drawbacks and provides a desirable servo steering force with a simple mechanism.

According to the invention, a detector is used in conjunction with a cylinder-piston unit that functions as a steering damper and as a device for generating auxiliary force (power steering). According to the invention, the detector is also formed integrally with the piston of the cylinder-piston unit. The hydraulic control of the cylinder-piston unit takes place via a three-position switching valve, so that the return amount of the hydraulic medium is throttled as a function of the speed.

In this way, according to the present invention, the detector does not detect rotational motion but only linear motion, so it can be constructed easily and inexpensively, and it is not necessary to directly connect the detector to the steering gear mechanism. The advantage is that safety is increased when operating the detector.

Furthermore, according to a preferred embodiment of the invention, the detector is formed integrally with the cylinder-piston unit of the steering damper. The above-mentioned detector can be easily constructed by using, for example, a plate spring arranged in a sandwiched manner and immovable contacts arranged at a predetermined distance on both sides of the plate spring.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 schematically shows the front axle of a motor vehicle with a steering gear mechanism and various components and control devices used in a servo steering system. 10 indicates a steering shaft, and 11 indicates a steering gear mechanism. Although this steering gear mechanism is not shown in detail, it acts on the tie rod joint 12 to control the running direction of the wheels 13. The reference numeral 14 designates a two-chamber cylinder-piston unit of a steering damper which functions as a servo device in this embodiment. The cylinder of this cylinder-piston unit 14 is rigidly fixed to the axle of the motor vehicle via fastening means 15, while the piston is connected via a sensor 16 and a lever 17 to the joint 12 of the tie rod.

The cylinder-piston unit 14 has an electrically controllable solenoid valve 2 in a regulating device 22.
The hydraulic medium obtained from a hydraulic medium container 23 is supplied via 0,21. This hydraulic medium container 23 can also be part of a central hydraulic system used in combination with a shut-off protection device.

The electronic control unit 25 receives a steering direction signal obtained via two inputs 26, 27, an ignition signal obtained via an input 28, and a speed signal obtained via an input 29, respectively. 2 outputs 3
0 and 31 are connected to the excitation windings of two solenoid valves 20 and 21 provided in the regulating device 22, and the other output 32 is connected to a warning lamp 34 indicating that a fault has occurred via a lead wire 33. Connected.

The control device 25 further includes gating circuits for processing the individual electrical signals, amplification circuits for amplifying the output signals, and safety circuits for identifying, indicating and reacting to faults. In detail, this control circuit 25 is configured as follows. Both inputs 26, 27 are respectively connected to logic gates 35, 36 each having an inverting input and a non-inverting input. The inputs 26, 27 are connected to the non-inverting inputs of both logic gates. On the other hand, the other non-inverting input of each logic gate 35, 36 is the AND gate 3.
The input of the AND gate 37 is connected to the output of 7, and the input of the AND gate 37 is connected to the input 28, to which the ignition signal and the speed signal are applied.
This is the same input as No. 29.

Timing elements 38 and 39 are connected to the outputs of logic gates 35 and 36, respectively, and the timing elements generate output signals having a constant pulse width in response to the trigger signal. An AND gate 40, 41 is connected behind the two timing elements 38, 39, the outputs of which are connected via drive circuits 42, 43 to the excitation winding of the solenoid valve provided in the regulating device 22. Both drive circuits 42,
The output of 43 is further connected to a safety circuit 45. The output of the safety circuit is connected to the warning lamp 34 and to the other inputs of AND gates 40 and 41 via an inverter 46, respectively.

Furthermore, the outputs of both timing elements 38, 39 are connected via timing elements 48, 49, respectively, to the inverting inputs of logic gates 35, 36. The logic gate 35,3
After 6, timer elements 38 and 39 are connected, respectively, as described above.

The operation of the circuit illustrated in FIG. 1 is as follows. Steering wheel or steering shaft 10
When rotated to the right, a signal is generated which is input by the detector 16 to the input 26 of the control device 25.
This signal is applied via a logic gate 35 to a timing element 38 configured as a monostable multivibrator, whose output signal reaches a drive circuit 42 via an AND gate 40. This causes the solenoid valve 20 to actuate and the piston of the cylinder-piston unit 14 to move accordingly.
Hydraulic pressure is applied to the cylinder of unit 14 by solenoid valve 20 until timing element 38 shuts off. If the pressure impulse acting on unit 14 is large enough, the contacts on the opposite side of detector 16 will react. Thereby the other solenoid valve 2 of the regulating device 22
In order to prevent the gate 1 from operating, the output signal of the timer 38 sets a timer 49 to shut off the gate 36 for a predetermined period of time. In this way, the timing elements 38 or 39 are enabled to shut off the other when one of them is activated.

In order to operate the power steering as shown in FIG. 1 only in the low speed range and when the ignition is activated, both logic gates 35 and 36 are activated according to the position of the ignition switch and when a predetermined low speed signal is activated. Make it work when it appears.

The safety circuit 45 connects both solenoid valves 20 of the regulating device 22,
It functions to monitor the control signals of 21. For safety reasons, both solenoid valves must not be energized for too long or both at the same time. For this reason, the safety circuit 45 is provided with a timing element (preferably an exclusive OR gate), by means of which a warning signal is applied to the warning lamp 34 in the event of a fault and also to the drive circuits 42, 43.
is blocked.

FIG. 2 shows a more detailed detector than in FIG. 1 for use in combination with the cylinder-piston unit 14. The end of the housing of this detector 16 is connected to a rod 51. A leaf spring 52 is attached to this housing.
This leaf spring is frictionally connected to the piston 53 of the cylinder-piston unit 14, optionally insulated. This leaf spring is preferably composed of two leaf springs, and each leaf spring is arranged so as to sandwich a piston. Two switching contacts 54, 55 are provided on the opposite side of this leaf spring. As the steering shaft 10 rotates, the piston 53 moves in accordance with the force and direction obtained from the rod 51 via the lever 17 in FIG. Since the leaf spring 52 and the piston 53 are frictionally connected, the leaf spring 5
2 also moves and its contacts 54 and 55 are fixed contacts 5
6 and 57, and a switching signal is generated. As a result, the solenoid valves 61 and 62 operate, and the piston 5
3. Assistive force can be obtained for movement, that is, steering.

For example, when the steering shaft 10 is rotated to the right, a leftward force acts on the rod 51, contacts 54 and 56 come into contact, and the electromagnetic valve 62 is actuated to provide an auxiliary force for moving the piston 53 to the left.

When steering is completed, the steering shaft 10 returns to its original position, the detector 16 assumes the neutral position shown in FIG. 2, and the electronic control unit 25 also returns to its initial state. Subsequent rotation of the steering shaft to the right is similar to that described above, and conversely, when the steering shaft is rotated to the left, the opposite contact and the other solenoid valve are actuated to perform the same steering operation.

If the switching width (rotation) of the steering shaft 10 is large, the amount of movement of the piston 53 will be large, which will affect the damping characteristics of the steering damper (the steering damper is combined with the cylinder of the servo device in this embodiment). Buffer width limiting disks 58 and 59, which function as buffer members such as rubber, are attached to the housing 50 of No. 16.
Due to the damping effect of the discs 58 and 59, the amount of movement of the piston 53 within the housing 50 of the sensor 16 during steering wheel rotation is reduced to the contact points 54 and 56.
Alternatively, the width of movement is limited to a distance sufficient to bring 55 and 57 into contact.

The piston of the cylinder shown as cylinder-piston unit 14 has a block 60 shown in dotted lines in FIG. This block shows that the detector can be constructed integrally with the piston, and in this case, the force acting on the piston 53 can be directly detected by constructing the detector with, for example, a pressure-sensitive piezo element. Therefore, there is an advantage that frictional loss of the detector, such as that occurring between the leaf spring 52 and the piston 53, is reduced and safer operation is obtained. Note that the detector may be constructed using Hall elements or piezo elements instead of the double contact switches 52, 54-57.

FIG. 2 shows three-position switching solenoid valves 61 and 62, which are different from the solenoid valves 20 and 21 shown in FIG. In parallel with each solenoid valve, a back pressure valve 63,
64, each of which performs the function of a so-called foot valve of the steering damper. These back pressure valves operate only when the cylinder chamber of the cylinder-piston unit 14 connected to each valve becomes larger, and the back pressure valves operate only when the cylinder chamber of the cylinder-piston unit 14 connected to each valve becomes larger. Refill the cylinder chamber with liquid.

FIG. 3 shows a gate circuit connected to the drive circuit of the solenoid valve. These circuits can operate each solenoid valve at two different levels. The same signal inputs as well as the same parts as shown in FIG. 1 are provided with the same reference numerals.

Both inputs 26, 27 of the control device are connected to AND gates 70, 71, respectively, and controllable amplifiers 72, 73 are connected after these AND gates. The output of this amplifier includes the solenoid valve 61 shown in FIG.
62 excitation windings are connected. The output signal of AND gate 37, which receives the ignition and speed signals shown in the circuit of FIG. 1, is supplied to AND gates 70, 71 and amplifiers 72, 73.

When the ignition is activated and the parking servo steering system is in the operating speed range, the solenoid valve operates from the no-current position shown in Figure 2 by operating the amplifier at current level i1. Moved to position ``'' where it can be started. When a signal is generated by the detector 16, it is applied to the gates 70, 71 and the amplifiers 71, 73 switch to the current level i2, thereby causing the respective solenoid valve 6 to
1 or 62 is the cylinder piston unit 14
Switches to the "" position where liquid can be fed to each cylinder chamber. The same holds true for the parking servo steering function, in which the ignition switch is engaged and a low speed signal is applied to the AND gate 37.

The three-position solenoid valve is preferably used in cases where the hydraulic balance of the steering damper has to be narrowed down to a greater extent than usual in a small speed range, which is the range of the parking servo steering function. As a result, relatively large damping forces are generated even at low adjustment speeds of the pistons of the cylinder-piston unit 14.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a schematic configuration of a servo steering system for an automobile according to the present invention, FIG. 2 is a sectional view showing the relationship between the detector and cylinder piston unit used in FIG. 1, and FIG. 2 is a block circuit diagram showing details of the control device of the FIG. 1 apparatus; FIG. 10... Steering shaft, 11... Steering gear mechanism, 12... Tie rod joint, 14...
Cylinder piston unit, 16...detector,
20, 21...Solenoid valve, 22...Adjusting device, 23
... Pressure medium container, 25 ... Control device, 34 ...
Warning lamp, 38, 39... Timing element, 42, 4
3... Drive circuit, 45... Safety circuit, 53... Piston, 54, 55... Switching contact, 56, 57
...An immovable point of contact.

Claims (1)

[Scope of Claims] 1. A steering shaft, a steering gear mechanism, a tie rod for transmitting the motion obtained by the steering shaft and the steering gear mechanism to the wheels of an automobile, a piston being drivingly connected to the tie rod, and a cylinder. and a two-chamber cylinder-piston unit used as a hydraulic steering damper coupled to the vehicle body, and the two chambers of the cylinder-piston unit are connected to an adjusting device of a servo device via a hydraulic pipe, and are connected to the adjusting device. In a servo steering system for an automobile in which a steering assist force is generated by applying a control pulse obtained from an electronic control unit operated by a detector for detecting a steering direction, the detector 16 is provided in the piston part 53. A servo steering system for an automobile, characterized in that the relative displacement between a tie rod and a piston is detected to detect a steering direction, and the electronic control unit is operated to generate a steering assist force. 2. The servo steering system for a motor vehicle according to claim 1, wherein the amount of pressure medium returned from the chamber of the cylinder-piston unit 14 is throttled when the motor vehicle is at low speed. 3. The servo steering device for an automobile according to claim 2, wherein the feedback amount is throttled using a three-position switching valve. 4 The detector has double contact switches 52, 54.
~57. The servo steering device for an automobile according to claim 1, wherein the servo steering device is provided with a Hall element or a piezo element. 5. The servo steering device for a motor vehicle according to claim 4, wherein the double contact switch is provided with a leaf spring having contacts. 6. The output of the detector 16 is transmitted to timing elements 38, 39.
A servo steering device for a motor vehicle according to any one of claims 1 to 4, as provided in Claims 1 to 4. 7. The servo steering device for a motor vehicle according to claim 6, wherein the timing elements 38, 39 are capable of shutting off the other when one of them is operating. 8. The automobile according to any one of claims 1 to 7, wherein the supply of hydraulic medium to the cylinder piston unit 14 can be controlled according to the position of the ignition switch and the speed signal. servo steering device. 9. Claims 1 to 8, wherein the electronic control device 25 is provided with a safety circuit 45 that responds to an output signal for operating the solenoid valve of the regulating device 22 and monitors the safe operation of the solenoid valve. The servo steering device for an automobile according to any one of the preceding paragraphs. 10. A steering shaft, a steering gear mechanism, and a tie rod that transmits the motion obtained by the steering shaft and steering gear mechanism to the wheels of an automobile;
It is equipped with a two-chamber cylinder-piston unit used as a hydraulic steering damper, in which a piston is drivingly connected to the tie rod and a cylinder is connected to the vehicle body, and the two chambers of the cylinder-piston unit are connected to a servo device adjustment device through a hydraulic pipe. A servo steering system for a motor vehicle, in which a control pulse obtained from an electronic control unit connected to a detector for detecting a steering direction is applied to the adjusting device to generate a steering assist force. A servo steering system for an automobile characterized in that the detector 16 is provided in the piston part 53 and detects the relative displacement between the vehicle body and the piston to detect the steering direction and also operates the electronic control device to generate a steering assist force. Device. 11 The detector 16 is formed integrally with the cylinder piston unit 14.
The servo steering device for an automobile according to item 0.